1. Field of the Invention
The present invention generally relates to an apparatus and method for providing a Subscriber Identity Module (SIM) Application Toolkit (SAT) service in a mobile communication system, and in particular, to an apparatus and method for providing an SAT service in a mobile communication system.
2. Description of the Related Art
In general, an SAT refers to a series of commands and procedures for providing a specific service of a network operator to users of mobile communication terminals. The SAT functions as an interface for mutual communication between a SIM and Mobile Equipment (ME) (i.e., a mobile communication terminal minus the SIM).
An SAT service can be provided only when both the SIM and the ME support the SAT. In an SAT session, the SIM transmits a processing command to the ME to start communication with a user of a mobile communication terminal. As defined in the 3rd Generation Partnership Project (3GPP) Technical Specification (TS) 31.111 Universal Subscriber Identity Module (USIM) Application Toolkit (USAT), 3GPP TS 11.14 Specification of the SIM Application Toolkit for the Subscriber Identity Module-Mobile Equipment (SIM-ME) Interface, commands for operating the SAT include a proactive command directed from the SIM to the ME and an envelope command directed from the ME to the SIM.
The proactive command includes Display Text, Get Inkey, Get Input, More Time, Play Tone, Poll Interval, Refresh, Set Up Menu, Select Item, Send Short Message (SM), Send Supplementary Service (SS), Send Unstructured Supplementary Service Data (USSD), Set Up Call, Polling Off, Provide Local Information, Set Up Even List, Perform Card Application Protocol Data Unit (APDU), Power Off Card, Power On Card, Get Reader Status, Timer Management, Set Up Idle Mode Text, Run At Command, Send Dual Tone Multi-Frequency (DTMF), Language Notification, Launch Browser, Open Channel, Close Channel, Send Data, Get Channel Status, Service Search, Get Service Information, and Declare Service. The envelope command includes Data download to SIM, Menu Selection, Call Control by SIM, Timer Expiration, and Event Download.
Service providers combine such commands with each other and transmit/receive the combined commands through a Short Message Service (SMS) to provide specific information services. Service providers usually develop their own specific services such as connection of a call to a specific service number through the combination of the commands to provide SIM applications.
A conventional terminal can only provide a built-in SAT service implemented in advance by a service provider through an SAT for a specified service in a SIM. Accordingly, user of the mobile communication terminal can only select an SAT menu provided in the terminal and request a specified service such as weather information and traffic information, by sending a text message through the SAT menu or by using the calling function of the mobile communication terminal.
Diverse SAT services are being developed according to the demand of users and the development of terminals. However, the storage space of a SIM card is not large enough to store the diverse SAT services.
Information required for detecting the results of an SAT service may be requested using a Short Message Service (SMS) message or a Multimedia Messaging System (MMS) message. In this case, a mobile communication terminal must be allocated a channel for the SMS message or the MMS message, which may cause frequent requests for radio resources.
Result information generated during an SAT service may be received using an SMS message or an MMS message. In this case, a mobile communication terminal must terminate an SAT service mode and switch to a mode for detecting the SMS message or the MMS message, which causes an inconvenience to the user.
Unstructured Supplementary Service Data (USSD) has been introduced to support a provider-defined service, which is used to transmit information or specific commands from a GSM (Global System for Mobile communications) network.
There are a variety of SSs (Supplementary Services) in the GSM, which can be operated using a series of strings. Examples of the service operation using a series of strings include service activation/deactivation and interrogation. Input strings are specified in the GSM standards, which are interpreted by a mobile communication terminal prior to transmission to the network.
In the case of the USSD, if a string is input by a user, a mobile communication terminal fails to interpret the input string and transmits the corresponding data to the network. The mobile communication terminal receives information from the network and displays the received information. A command can be transmitted from the mobile communication terminal to the network, which enables communication with the GSM network.
The data transmission rate of the USSD service is up to about 7 times higher than that of the SMS. Both the SMS and the USSD use a signaling channel. The SMS allocates one channel to each message. However, the USSD is session-oriented and the connection is maintained until it is terminated by the user.